The employee appeals from the compensation judge’s finding that the employee’s October 1, 2004, low back and right hip injury was temporary in nature and had resolved by May 9, 2005, and from the judge’s consequent denial of wage loss benefits, medical expenses, and a rehabilitation consultation.  We affirm.

Prior to the 2004 work injury that is here at issue, John McMahon was subject to low back and leg symptoms due to an earlier claimed work injury sustained while working for Action Disposal System, Inc./BFI on August 8, 1995.  On that date, Mr McMahon fell from a recycling truck and struck his low back on a cement curb.  Following that injury, Mr. McMahon received extensive care from numerous physicians and medical facilities.  His complaints primarily were of persistent left-side low back pain that radiated into his left buttock and around his left SI joint.  Mr. McMahon also intermittently experienced bilateral low back pain and pain in both legs.  Treatment through July 6, 1998, included physical therapy, numerous medications, CT and MRI scans, an EMG, a bone scan, epidural steroid injections, and left SI joint injections.  Mr. McMahon apparently continued to receive treatment for his 1995 work injury into 2002, undergoing a repeat MRI scan in January of that year, followed by several months of physical therapy at the Physicians Neck and Back Clinics.^[1]

In January 2004, Mr. McMahon [the employee] began working as a loss prevention officer for SuperValu/Cub Foods [the employer].  On October 1, 2004, while pursuing two shoplifters into the employer’s parking lot, the employee slipped and fell, landing hard on his right hip and buttocks.  At the time of his injury, the employee was thirty-four years old and was earning a stipulated weekly wage of $508.46.^[2]

The employee immediately commenced treatment at Apple Valley Medical Center, eventually coming under the care of family practitioner Dr. John Decker.  The employee complained initially of pain in his right hip, elbow, wrist, and knee.  X-rays of the right wrist and hip were read as negative for fracture, and the bones and joint spaces of the right hip appeared normal.  On October 12, 2004, Dr. Decker diagnosed a neck, hip, and low back strain, prescribed medications, and recommended rest and heat.  In follow-up three weeks later on November 4, 2004, the employee complained of right lateral hip pain radiating to the lower leg.  Dr. Decker noted that the employee’s lumbar area was “ok except at [the] sciatic notch.”  He diagnosed right hip and leg pain and arranged for a referral to an orthopedist.

On November 16, 2004, the employee was seen by orthopedist Dr. David Boxall.  The employee told Dr. Boxall that ever since his fall on October 1, 2004, he had had right lateral hip pain that bothered him at night and with walking.  Dr. Boxall diagnosed bursitis of the right hip and administered a cortisone injection.  The employee evidently experienced some temporary relief from the injection but was seen for recurrent symptoms on December 13, 2005, by Dr. Boxall’s associate, Dr. Mark Sigmond.  Dr. Sigmond noted that the employee had exquisite tenderness over the greater trochanteric bursa area of the right hip and administered a second injection.

The employee missed very little time from work following his injury but continued to experience persistent right hip and leg pain.  By February 2005 the employee’s pain complaints included also the right side of his low back and buttock, and Dr. Decker referred him for an MRI scan of the lumbar spine and right hip.  The MRI of the right hip was conducted on March 8, 2005, and was viewed as normal.  The scan of the lumbar spine reflected a small L5-S1 disc herniation, with slight compression of the left S1 nerve root, and some asymmetric bulging of the L4-5 disc on the right, which mildly displaced the right L5 nerve root centrally.

The employee returned to Apple Valley Medical Center on March 25, 2005, and reported that his back had “popped out” as he was bent over working on his van at home.  He complained of pain in his lower mid back that radiated down his left leg, leaving him unable to walk.  He was given an injection for his pain and instructions to follow up with his doctor.

The employee returned to see Dr. Decker on April 26, 2005, complaining of low back and hip pain this time on the right.  Dr. Decker’s notes indicate expressly that he was aware of no previous history of right-side back pain in the employee’s experience, although he did note that the employee’s lumbar MRI had been compatible with right-side sciatica.  He continued to prescribe medications and referred the employee for physical therapy.

On May 9, 2005, the employee was examined at the request of the employer and insurer by orthopedist Dr. Thomas Raih.  Dr. Raih obtained a history from the employee, reviewed the employee’s medical records, and conducted an orthopedic neurologic examination.  In a report dated May 16, 2005, Dr. Raih diagnosed, “via MRI report,” a small right-side L4-5 disc bulge, which mildly displaced the right L5 nerve root.  He also reported an incidental finding of a small disc herniation on the left at L5-S1, which did not correlate with his symptoms.  Dr. Raih noted that the employee had fallen and had a direct contusion to the right low hip on October 11, 2004, and that the employee’s “situation regarding the injury to the right low back and buttocks area has resolved and he does not require any further treatment.”  The doctor concluded that the employee had reached maximum medical improvement [MMI], was capable of working at his loss prevention job with no specific restrictions, and had no permanent partial disability related to his work injury.

The employee underwent a repeat MRI of the lumbosacral spine and an MRI of the sacrum and coccyx on June 20, 2005.  The MRI of the lumbosacral spine was read as showing mild to moderate disc degeneration at L5-S1 with a small broad-based central posterior disc herniation and no significant narrowing of the central canal.  Comparison with the previous MRI of March 8, 2005, showed no significant interval change.  The MRI examination of the sacrum, coccyx, and sacroiliac joints was read as negative.

The employee evidently continued working for the employer and missed occasional time from work.  He was paid intermittent temporary partial disability benefits by the employer and its workers’ compensation insurer through most of July 2005.  On July 20, 2005, the employee filed a claim petition, seeking additional wage loss benefits, medical benefits, and rehabilitation benefits consequent to his work injury of October 1, 2004.  The employer and insurer admitted that the employee had sustained a mild right hip injury on October 1, 2004, but they contended that the employee had completely recovered from that incident.  They denied primary liability for the employee’s alleged low back injury and alleged, in the alternative, that, if the employee had injured his back in the fall at work, the injury was merely a temporary aggravation of a pre-existing condition.  They alleged also that the employee had sustained a superseding, intervening injury at home on March 25, 2005.

In August 2005, Dr. Decker referred the employee for an EMG of his right lower extremity and a therapeutic and diagnostic right SI joint arthrography.  The employee’s EMG was conducted on August 8, 2005, and was reported to be normal.  On August 25, 2005, the radiologist reported an arthrographically normal right SI joint also, and the employee reported complete relief of his symptoms immediately after the procedure.

On August 31, 2005, the employee began a physical rehabilitation program at Physician’s Neck and Back Clinics under the direction of Dr. Andrew Maas.  In an initial assessment prepared on that date, Dr. Maas diagnosed mechanical low back pain, lumbar degenerative disc changes by imaging, lumbar radiculitis, and deconditioning syndrome.  Dr. Maas recommended a nine-week program of focused exercise treatment intended to decrease the employee’s pain and improve his tolerance of physical activities.

In a letter to the employee’s counsel on October 18, 2005, Dr. Decker essentially concurred with Dr. Maas’ diagnosis and opined that the employee’s work injury was a substantial contributing cause of and factor in the employee’s disability and condition.  However, acknowledging the employee’s March 25, 2005, incident at home and his history of disc bulging going back to 1995, Dr. Decker stated, “I am unconvinced at this point that all of the current symptoms are necessarily caused by the work injury, nor do I know if the injury that was sustained while working on his van has anything to do with that.”  He stated further that “[d]ue to the knowledge that he had had bulging discs previously, this second injury could have been entirely independent from the work injury, and not a sustaining factor.”  Dr. Decker did not believe that the employee had reached MMI, as he had not yet completed the therapy program recommended by Dr. Maas, and he felt that it was too early to determine whether the employee had sustained a permanent partial disability.

The employee was examined by Dr. Raih for a second time on November 21, 2005.  The doctor was provided with additional medical records as well as a disc of video surveillance conducted on the employee between January 7 and October 8, 2005.  In a report dated November 30, 2005, Dr. Raih specifically opined that the employee’s October 1, 2004, work injury was a temporary exacerbation of the employee’s underlying condition of degenerative lumbar disc disease and that the injury had resolved by May 9, 2005.  He found that the employee’s subjective symptoms outweighed his objective findings and that the employee had not been totally disabled from all work activities since May 9, 2005.  Dr. Raih noted that, objectively, the employee had near-full motion with no neurologic deficit.  He did report that the employee should not do any heavy lifting on a repetitive basis, but he related the need for that restriction to the employee’s mild degenerative disc disease that predated his work injury of October 1, 2004.  The doctor opined that the employee had reached MMI as of May 9, 2005, and that he had sustained no permanent partial disability as a result of the injury.  Finally, Dr. Raih was of the opinion that only that medical treatment provided through May 9, 2005, had been reasonable and necessary.  Treatment after that date, he concluded, was not related to the October 1, 2004, incident.

The employee completed twenty-four rehabilitation sessions at Physicians Neck and Back Clinics, and Dr. Maas issued a discharge report on November 28, 2005.  Although Dr. Maas reported that the employee had objectively made excellent progress, the employee continued to report that his subjective symptoms remained relatively unchanged.  With respect to work activities, Dr. Maas authorized the employee to remain off work through December 20, 2005, to allow time for the exercise-induced inflammation to gradually decrease.  He then released the employee with a thirty-pound lifting restriction, noting that he also should avoid repetitive stooping and bending and should change positions frequently.  Dr. Maas anticipated that the employee would be able to return on January 2, 2006, to his usual level of unrestricted activity.

The employee’s claim for benefits came on for hearing before a compensation judge on December 5, 2005, and January 6, 2006.  Issues at hearing included the following: (1) whether the employee had sustained a low back injury on October 1, 2004; (2) whether the employee’s right hip and/or low back injury was temporary or ongoing; (3) whether the employee had been temporarily totally disabled continuing from August 21, 2005; (4) whether the employee had work restrictions and, if so, whether the work injury of October 1, 2004, was a substantial contributing factor in those restrictions; (5) whether the employee had reached MMI; (6) whether the employee had sustained a reduction in earning capacity due to his work injury of October 1, 2004, such as would entitle him to temporary partial disability benefits from October 1, 2004, through July 23, 2005; (7) whether all of the employee’s medical expenses incurred after March 9, 2005, were reasonable and necessary and causally related to his work injury; and (8) whether the employee is entitled to a rehabilitation consultation.

By findings and order filed March 17, 2006, the compensation judge concluded in part that the employee injured his low back and right hip on October 1, 2004, but that that injury was temporary in nature and had resolved by May 9, 2005.  The judge therefore denied the employee’s claim for wage loss benefits, payment of medical expenses incurred after May 9, 2005, and a rehabilitation consultation.  The employee appeals.

On appeal, the Workers’ Compensation Court of Appeals must determine whether “the findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.”  Minn. Stat. § 176.421, subd. 1 (2004).  Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.”  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.  Id. at 60, 37 W.C.D. at 240.  Similarly, findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.”  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).

At Finding 1, the compensation judge concluded that the employee’s low back and right hip injury were temporary in nature and had resolved by May 9, 2005.  In a memorandum accompanying her findings, the judge explained that, “[w]hile it is entirely possible that the employee sustained an ongoing injury to the low back on October 1, 2004, the evidence is not sufficiently persuasive to support this conclusion.”  She indicated that, in reaching her conclusion, she had relied on Dr. Raih’s opinions, which she believed were based upon an accurate history, noting that Dr. Decker did not fully explain his understanding of the significance of the employee’s pre-existing condition and how it entered in to his opinion as to the duration of the employee’s lumbar injury.  Nor did Dr. Maas, the judge noted, provide any opinions regarding causation of the employee’s condition or restrictions.  Finally, the judge explained that she found the employee’s testimony to be inconsistent and lacking in candor, both at the hearing and in his deposition testimony.  The employee contends on appeal that the judge’s decision is clearly erroneous and unsupported by substantial evidence.  Dr. Raih’s opinion, he argues, is not well founded and should not have been afforded evidentiary value by the compensation judge.  The employee reiterates that he had substantial low back pain and bilateral radicular symptoms that remained unchanged both before and after May 9, 2005, and that this status is evidenced by the medical records of his treating doctors.^[3]  We are not persuaded.

The competency of a medical expert to provide an expert opinion depends upon both the extent of the expert’s scientific knowledge and the expert’s practical experience with the matter that is the subject of the expert opinion.  Reinhardt v. Colton, 337 N.W.2d 88 (Minn. 1983).  Dr. Raih is an orthopedic surgeon, and he examined the employee on two occasions.  On both of those occasions he obtained a history from the employee, reviewed the relevant medical records, and performed a physical examination.  As a rule, this level of knowledge is generally sufficient to afford foundation for the opinion of a medical expert, see, e.g., Caizzo v. McDonald’s, 65 W.C.D. 378 (W.C.C.A. 2005), and we conclude that Dr. Raih’s examination of the employee and review of his medical records provided the doctor with very ample foundation to render a competent opinion.  Moreover, the compensation judge specifically found the employee’s own testimony to be inconsistent and lacking in candor.  The judge was not required to credit either the employee’s own testimony or the medical records of his treating physicians over the opinions of Dr. Raih.  This court has frequently reiterated its deference to the perspective of compensation judges in matters of credibility, see Brennan v. Joseph G. Brennan, M.D., 425 N.W.2d 837, 839-40, 41 W.C.D. 79, 82 (Minn. 1988) (assessment of a witness’s credibility is the unique function of the trier of fact), and in the choice of medical opinion on which to rely, see Nord v. City of Cook, 360 N.W.2d 337, 342-43, 37 W.C.D. 364, 372-73 (Minn. 1985) (a trier of fact’s choice between experts whose testimony  conflicts is usually upheld unless the facts assumed by the expert in rendering his opinion are not supported by the evidence).

The ultimate question for this court is whether substantial evidence supports the compensation judge’s finding that the employee’s low back and right hip injury were temporary in nature and had resolved by May 9, 2005.  The judge accepted the opinions of Dr. Raih on this issue, while specifically rejecting those of Dr. Decker and Dr. Maas.  Given the record of the employee’s substantial and lengthy medical treatment prior to his injury of October 1, 2004, the judge’s assessment of the employee’s credibility, and the judge’s choice of medical opinions, we affirm the judge’s decision in its entirety.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.